A series of automatic processes is known from the prior art for determining data of a slaughtered animal body in its splitting plane along the backbone by means of optical image processing for subsequent classification and quality rating.
Therefore, the documents DD 298 310 A5/DE 41 31 556 C2 and DE 41 09 345 C2 describe methods for determining or analysing halves of slaughtered animals by means of image processing, wherein the outer contour, layer of fat, meat and back fat ratio are determined, in that images are recorded of the entire half of slaughtered animals including the backbone and all the intermediate vertebrae layers. As a fixed point for determining the parameters for splitting and classifying the slaughtered animal body, the starting point is the sacrum of the spinal column, which is also determined in the same way as the other vertebrae by means of object analysis, wherein during the actual processing it is not always possible to select the contours required for analysis in a sufficiently reliable manner.
The document DE 197 33 216 C1 describes a method for evaluating halves of slaughtered animals using optical image processing, which renders it possible based on the standard two-point method to carry out a classification using an optical image evaluation of the extended loin region whilst excluding subjective error sources.
A method of evaluating slaughtered animal halves by means of optical image processing is also known from the document DE 198 47 232 C2, wherein a photogrammetric method is used as a simulation of the conventional two-point method. In the loin and ham region, two clearly defined points, of which the first point is the body-side end of the pin bone, the second point is the body-side end of the MGM (Musculus Glutaeus Medius), and a straight line with the direction of the middle progression of the back fat are recorded photogrammetrically. For actual evaluation purposes, the lengths of partial sections are used which are provided on a perpendicular on the straight line, which is displaced in parallel with the pin bone, at the level of the second clearly defined point through the layer of the back fat. Although in the case of this method the subjective measuring errors of the manually performed two-point method are eradicated, it is a prerequisite that the required contours and structures are reliably recognised by the optical image processing.
A further method is known from document DE 199 36 032 C1 wherein it is ensured that the quality of halves of slaughtered animals, in particular of slaughtered pigs, is automatically assessed using optical image processing and with respect to the known methods a greater level of reproducible estimating accuracy is achieved which can only be influenced insignificantly by errors during the method of splitting the slaughtered animal and cannot be influenced by imaging which is not absolutely perpendicular to the splitting plane, wherein an optical image of the slaughtered animal half in the splitting plane is evaluated in the area of the ham region and loin region photogrammetrically on the basis of specific clearly defined reference points.
The spinal column, the pin bone, the thinnest layer of fat at the MGM and the contours of the back fat in the selected region are used as the clearly defined reference points. The muscle-meat percentage which is decisive for assessing the quality is calculated by the summation of part lengths, which are set in ratio with respect to each other and are perpendicular to the straight progression of the canal of the spinal cord in the region of the meat and layer of fat using constants, which are ascertained by means of regression calculations for each term, and a basic constant. Although within the scope of the method the measurement value for the amount of fat (S) is determined in accordance with the legal regulations at correct points, the amount of meat (F) is not determined, as a result of which the muscle-meat percentage (MF %) is not calculated using the official formula, thus classification into the trade classes is not possible.
A method of determining the trade value of the pieces of pig carcasses is known from the document DE 199 52 628 A1, wherein weights, weight and meat percentages of pieces of ham, cutlet, removed cutlet, fillet, shoulder, shoulder area, belly and/or other pieces which can be traded or further processed separately are determined by means of online-evaluation of pig halves. In order to implement the method, predictors which describe the body structure are determined, which predictors result from the progression of the outer contour of the pig half and, derived therefrom, the area, position and the progression of the spinal column and, derived therefrom, the lengths and areas of part regions of the slaughtered animal body and one obtained for the pig halves, information regarding the amount of fat and representing the relative thickness and the progression of the approximate total subcutaneous fat layer of the back region. The predictors are set in relation to each other taking into consideration statistical relationships existing between them, as a consequence of which the weight of pieces which are of interest, their weight percentage and meat percentages of the total weight of the carcass are to be determined online in the slaughter line. During the course of the method the complete pig half must be recorded by video and the image object processed and evaluated, which is costly, in order to determine merely the trade value. Owing to the large image region over the entire splitting plane, the rate of evaluation is impaired and also the weights of pieces cannot be determined in a sufficiently accurate manner, and error recognition of contours and structures in the image region result in unrealistic values.
Furthermore, the patent application referenced as DE 103 58 487.0 describes a method of determining the quality and quantities of a slaughtered animal body which can be used to determine the trade classification, trade value, market value and quality and which satisfies the conditions of the relevant official directives and regulations. The result data of weight percentages from yields of the individual parts as acquired by tests on cut pieces of a sufficient number of carcasses are correlated together with the characteristic measurement values and parameters, including the total weight, which are determined by both halves of a carcass in the ham and loin region, and from this relational data is acquired and in the operating slaughterhouse a simulation calculation for estimating the yields of the individual parts is performed with this relational data taking into account the total weight of two associated halves of a carcass and the characteristic measurement values and parameters which are determined therefor specifically in the ham and loin region.
In one variation, the yields of the individual parts are estimated only on the basis of the characteristic measurement values and parameters which are determined specifically in the ham and loin region.
A common aspect of all of these known methods is that the fully automatic contour recognition algorithms which are used in image processing for identifying contours with complex structures inevitably have a certain error recognition rate. In fact, in the case of incorrectly identified contours a subsequent optimisation method can be employed when attempting to correct the errors which have occurred, wherein however, new evaluation errors generally occur with the newly determined contours, thus causing incorrect or erroneous data or values for subsequent calculations.